Straight Lines ...

$$n!=n(n-1)(n-2).....3.2.1$$

The positions of the first and the fifth digits in the number 83256479 are interchanged. Similarly the positions of the second and the sixth digits are interchanged and so on. Which of the following will be the third to the right of the seventh digit from the right end after rearrangement?

The area of a triangle whose vertices are $$(a, c+a), (a, c) $$ and $$(-a, c-a) $$ are 

The greatest number that can be formed by the digits $$7,0,9,8,6,3$$

In numbers from $$1 \ to\  100$$ the digit "$$0$$" appears ____________times.

In the series given below. count the number of 9s, each of which Is not immediately preceded by 5 but is immediately followed by either 2 or 3. How many such 9s are there?
1 9 2 6 5 9 3 8 3 9 3 2 5 9 2 9 3 4 8 2 6 9 8

What will be the difference between the first digit of the highest number as well as of the lowest number after the positions of the first two digits in each number are reversed?

How many combinations of two-digit numbers having 8 can be made from the following numbers?
8, 5, 2, 1, 7, 6

CE, GI, KM, OQ, ....

Which letter will be the fifth from the right if the first and second, the third and fourth and so on are interchanged among each other in the word "COMPANIONATE"?